Electromotor



June 14, 1938. E. VOGEL 2,120,914

ELECTROMOTOR Filed on. 4, 1955 Patented June 14, 1938 PATENT OFFICEEIECTBOMOTOB Ernst Vogel, Stockerau, Austria Application October 4;1935, Serial No. 43,583 In Austria November 19, 1984 1 Claim.

In electromotors operating in a liquid in the upright position, the deadweight of the rotor and, in case the motor serves for driving acentrifugal pump, also the dead weight of theirotating parts of thispump and the axial movement have to be compensated for. In the latterevent it is known to construct the pump in such a manner, that itproduces a hydraulic axial thrust which substantially corresponds in nagnitude to the weight but is exerted in the opposite direction. Howeverthis axial thrust varies with the different heads of the pump. Furtherit is known to provide the pump with a relieving plate whereby theweight of the revolving parts is balanced by the upward thrust of liquidpumped against the under side of said plate by the motor. However thisrelieving device is adapted for use in connection with pure feed-liquidonly, because impure or sandy water, when discharged through a smallopeningunderneath the relieving plate, would cause the plate to be wornor otherwise influenced unfavorably.

Compared with the above, the present invention relates to a relievingdevice for electromotors 25 working in a liquid in an upright positionand serving for the operation of any desired device for instancecentrifugal pumps. The invention consists in that the relieving plate,known per se, rotates in a liquid which is separated as tight- 30 ly aspossible from the outer liquid and which may be the liquid frequentlyenclosed in the rotor compartment for instance a lubricant or may be incommunication with the same. The relieving plate is arranged below orabove the rotor of 35 the electromotor independently of the principalcentrifugal pump driven by the motor and the liquid surrounding'theplate exerts a pressure underneath the relieving plate by means of aseparate pump which is also operated by the electromotor.

The pump driven by the electromotor may be of any convenient type, forinstance it may be a rotary piston pump, a centrifugal pump or anautomatic suction pump, or if desired a so-called water annulus pump.

The space enclosing the relieving plate and the pump or the chamber,surrounding the said space and closing the cycle of the pressure liquid,is surrounded by the outer liquid and thus is cooled. 50 In particular,a system of pipes for cooling the rotor-liquid is provided andsurrounded by the outer liquid.

Also the liquid contained in the rotor compartment and placed incirculation by a feed-device, rotating with the motor-shaft particularlya centrifugal wheel, and passing through the annular gap between statorand rotor is passed through the system of cooling pipes surrounded bythe outer liquid.

A constructional example of the invention is illustrated in the drawing,Fig. 1 being an axial section through the motor with relieving andcooling device, while Fig. 2 is the evolution of the section taken online AB of Fig. 1.

The rotor 2 of the electric motor is mounted on the shaft I and oppositethereto is arranged the stator 3 leaving a gap 4 between itself and therotor. The stator is enclosed in known manner within the fluid-tightcasing 5 and is shielded from the gap by means of the pressure sleeve 6.The top end of the casing is closed by a head, of which only theconnection-flange is illustrated and through which the wires pass in awatertight manner.

According to the invention, the relieving plate I, secured to the shaftI underneath the rotor 2, is arranged in a compartment 8 which is incommunication with the rotor compartment 9 containing the rotor 2 in themanner described hereinafter, so that the relieving plate I issurrounded by a pure liquid filling this compartment and this pureliquid being separated as completely as the nature of the abovementioned communication permits from the liquid L in which the electricmotor is operating.

The rotor-part II) of a pump, which may if desired be a inulti-stagepump and to which the liquid is supplied from below, is mounted on theshaft I underneath the relieving plate I. By means of the pump, theliquid is forced against the bottom face of the relieving plate 1 andthen escapes through a very narrow gap II between this bottom face and acounter-ring I2. The pressure below the plate I adjusts itselfautomatically by slightly lifting the relieving plate and thus varyingthe gap in such a manner, that the upward pressure balances the weightof the parts connected with it, such as the shaft I, so that therelieving plate is kept suspended.

The construction of the arrangement is such, that the relieving platecovers the top of a compartment I4 enclosed by a casing I3 andcommunicating through the bottom of the compartment at IS with a spaceI5 surrounding the compartment. In this arrangement, a portion of theliquid passes from the space I5 through the port I8 to the pump-runnerand into the compartment I4, in which it is subjected to pressure, andby way of the narrow gap II the liquid is forced into the space Itagain, thus performing a complete cycle as indicated by the arrows inFig. 1.

The relieving plate 1 rests on the counter ring i2 when the electromotorand the pump iii are at a standstill. The relieving plate is notappreciably worn, because the starting of the electromotor only takes avery short time. However in the case .of high-power motors when theweight of the parts is great, the relieving plate is preferablyprevented from resting on the counter ring I2. It is then advantageousto arrange a ball-bearing or other footstep bearing 32 of non-corrodingsteel which, if the motor and the pump in are at a standstill, keepsopen a very small gap I I (up to approximately 0.1 millimetre) andpermits the lift of the relieving plate and shaft and the parts mountedthereon during the operation. This bearing prevents the relieving plateI from resting on the counter-ring l2 even if motor and pump in operatein the reverse direction, so that in this respect the bearing and thenon-return valve represent alternating or supplementary means of servingthe same purpose.

The cooling of the circulating inner liquid is of great advantage to theaction of the relieving plate 1 and also of the footstep bearing, itprovided, as well as of the electromotor.

The considerable amount of heat generated in electromotors of this kind,particularly in electromotors of high-power owing, on the one hand tothe electric losses and on the other hand to the frictional contact ofthe rotating liquid with the walls of the stator and rotor, has to beabstracted for preventing the surpassing or the highest permissibletemperature, because the cooling by the liquid L surrounding theelectromotor is insuflicient.

According to a further feature of the invention the heat of the motor isjointly abstracted with the heat generated by the relieving plate and byany bearings that may be provided.

This cooling action is effected by conducting that portion of the liquidwhich passes from the rotor-compartment 9 through the channel 22 into asystem of cooling pipes 23, which enclose the space i preferably in anupright position and through which that portion of the liquid circulates(see also Fig. 2). In these cooling pipes 23 the liquid passes up anddown and finally passes through the channel 24 into the compartment 8.The compartments 8 and 9 are separated from each other by a slidingbearing, arranged in the rotor-compartment and comprising abearing-support 25, brasses 26 and liner 21. The liquid contained in thecompartment 8 communicates on the one hand by way of the gap 28 betweenrelieving plate I and easing 3| with the space l5 and on the other handa portion is sucked through sinuous grooves 30 and into the top part ofthe rotor-compartment in the direction of the arrows, Fig. 1, by meansof a feeder rotating with the motor-shaft, preferably by means of acentrifugal pump impeller 29 arranged outside the rotor 2. In thismanner the liquid is put in circulation through the annular gap 4,between liner 6 or pressure sleeve 6 and rotor 2, and through thedescribed cooling device by which the heat accumulated by the lubricantis delivered by way of exchange to the liquid L surrounding theelectromotor. After leaving the annular gap, the liquid flows into thecompartment 9 and from here through the channel 22 to the cooling device23.

It is practically impossible to perfectly and permanently pack, againstthe action of the pressure of the liquid surrounding the electromotor,one or more shaft-bearings which are lubricated preferably by a liquidlubricant or consistent grease. In order to remove this drawback, one ormore chambers are arranged in front of the space of these shaft-bearingstowards the rotor-compartment or towards the outer liquid and the actualconnections are established by narrow passages. In this way stuflingboxes are unnecessary and the bearinglubricant is mixed very-slowly onlywith the liquid in the rotor-compartment or with the outer liquid, sothat its lubrication is maintained for a very long time.

If this advantageous arrangement is used in the present invention forthe liquid in the rotorcompartment, the result will be that the'relieving action caused by the relieving plate 1 remains perfectlyeffective also if in the case of a longer operation, the inner liquidhas mixed with the outer liquid, because the relieving plate (contraryto a thrust-bearing) does not need any liquid lubricant. The footstepbearing is provided solely for the object above mentioned and may bedispensed with.

What I claim is In an electric motor, a casing containing a liquid, astator arranged in said casing, a rotorshaft also arranged in saidcasing, a rotor mounted on said rotor-shaft, means operated by saidrotor for circulating said liquid through the gap between the rotor andstator, a relieving plate connected with said rotor-shaft, a compartmentin said casing below said plate, a pump in said compartment adapted tosubject said plate to an upwardly directed liquid pressure, a stop inthe casing preventing closure of said compartment by said plate, andmeans for conducting the portion of said liquid passing through said gapto the vicinity of said pump, said casing being adapted to be arrangedin a second liquid and said conducting means being of circuitous formand arranged adjacent the portion of the casing contacting the secondliquid.

ERNST VOGEL.

